1. Field of the Invention
The present invention relates to a vacuum isolation valve, and more particularly, to a vacuum isolation valve for effectively maintaining the inside of a chamber in a vacuum state by selectively isolating a tube that transfers a chamber cleaning gas and minimizing abrasion of a sealing member installed at a blocking part that blocks the tube.
2. Discussion of the Related Art
In general, a process requiring high precision such as a semiconductor or Liquid Crystal Display (LCD) fabrication process takes place in a space isolated from the outside and maintained at a constant temperature, such as a chamber. When the process is completed inside the chamber, foreign materials remain due to a processing gas in the chamber. Thus a chamber cleaning gas is injected into the chamber and the remaining foreign materials are removed by the chamber cleaning gas. The chamber is connected through a connection means such as a cleaning gas ionization module and a tube and receives an ionized chamber cleaning gas from the cleaning gas ionization module.
Nitrogen trifluoride (NF3) is used as a chamber cleaning gas ionized in the cleaning gas ionization module in order to increase process throughput and a cleaning rate. However, the cleaning gas ionization module is vulnerable to abrasion and breakdown by nitrogen (N) and fluoride (F) ions of the nitrogen trifluoride in the course of ionization of the nitrogen trifluoride. As a consequence, the cleaning gas ionization module should be replaced with a new one periodically or aperiodically.
For efficient processing, the chamber should be kept suitable for ongoing processing and thus isolated from an ambient environment even during replacement of the cleaning gas ionization module. That is, the inside of the chamber should be kept vacuum and discharge of air and heat from the chamber should be prevented. If the air and heat are discharged from the inside of the chamber during replacement of the cleaning gas ionization module, the vacuum state and temperature are changed inside the chamber, thereby changing an ongoing process state in the chamber. Then the inner temperature of the chamber should be re-raised to a level suitable for cleaning, re-vacuuming, and processing. The resulting process delay significantly reduces an overall process throughput.
However, no equipment is conventionally installed at a tube that connects the chamber and the cleaning gas ionization module, which keeps the chamber isolated from the outside through selective isolation of the tube. Therefore, when the cleaning gas ionization module is replaced, the chamber may not be isolated from an ambient environment.